1. Field
One embodiment relates to a transmission optical system, an illumination optical system, an exposure apparatus, and a device manufacturing method. More particularly, one embodiment relates to a transmission optical system suitably applicable to an illumination optical system of an exposure apparatus for manufacturing devices such as semiconductor devices, imaging devices, liquid crystal display devices, and thin film magnetic heads by the lithography process.
2. Description of the Related Art
The main body of the exposure apparatus of this type is a considerably large device in whole and the required floor area for installation thereof is large. Furthermore, a light source used to supply exposure light (illumination light) to the exposure apparatus is, for example, a KrF excimer laser light source or an ArF excimer laser light source and the excimer laser light source is also a considerably large device. It is therefore often the case that the light source device is arranged with some distance from the exposure apparatus body, in the case of the exposure apparatus using the excimer laser light source.
There is then a proposed transmission optical system including a relay lens system and a plurality of plane reflecting mirrors, as an optical system for guiding the light emitted from an optical outlet port of the excimer laser light source, to an optical inlet port of the exposure apparatus body (e.g., cf. U.S. Pat. No. 5,731,577). This transmission optical system guides the light in a nearly parallel beam state emitted from the light source, to the exposure apparatus body and injects the light in the nearly parallel beam state into the exposure apparatus body.